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1N22.20 - Water Rocket

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​1N22.20 - Water Rocket

Title1N22.20 - Water Rocket

Demonstrate the conservation of momentum.

Assembly Instructions


If 2 liter rocket is sticking, use silicon grease on dry gasket.


2-liter rocket
To operate 2-liter rocket first launch with only air as the propellant, then with water and air to show the differences. Place entire setup on an AV cart and place in a safe part of the room aimed away from the lamps and anything that cannot get wet. The blast can cover 15 foot radius and the rocket can travel up to 30 feet. To load, attach bicycle pump to nipple under the launch stand. Place the empty 2-liter bottle over seal and close locking latch mechanism (requires practice). Fill the rocket with 5 pumps of air and release the latch.
To operate the 2-liter rocket with water and air as the propellant, repeat the above loading procedure while adding water before placing on the seal. Fill the bottle to the mark (about 100 ml) and pump 5 times. The launch can spray so stand sideways to the launch pad.

Small rocket
To operate small rocket, pour in a small amount of water (less than the level denoted 100 ft.) and place the base of the rocket over the tip of the air charging pump and push the lock ring forward to clamp the rocket to the pump. Pump up the rocket by operating the plunger (5-10 pumps). Fire the rocket by holding it well away from you and pointing it straight up, then pull back the lock ring. Be careful or you will get wet.
Try using air only in the first rocket launch, and then water with compressed air. Since mwater+air > mair only, water is the best propellant.

Setup Time10
Operation Time5
Preview Time5
Operation Instructions

A small hollow plastic rocket is filled partially with water and then charged with compressed air which is used to expel the water at high speed and provide the motive power. The rocket provides an excellent example of the principles of conservation of momentum.

Demo on DimeNo
PIRA 200Yes
Export Instructions (if different)
Category1 Mechanics
Subcategory1N - Linear Momentum and Collisions
KeywordsNewton's Laws, Newton's 3rd Law, Newton's third law
Construction Information
To shape the rubber cork into a gasket, use a high speed grinder.
pop bottle 2 L
pump - bicycle modified with launcher assembly
kite string attached to release pin
water - from the tap
water rocket PVC stand with bottle hook up
plastic water rocket (for export)
raincoat (optional)